1. Field of the Invention
The invention relates to oscillating sanding devices having a driving unit which is pneumatically controlled through a valve system and causes the work-plate or sanding table to perform reciprocating oscillatory or vibratory motions.
2. The Prior Art
It has already been proposed to use oscillating sanding devices of this kind for precision sanding or finishing, especially wet-sanding, because their very high vibratory frequency combined with a relatively low amplitude of oscillation makes these devices highly suitable for precision work. However, known systems of comparable construction are only suitable for finishing processes and are liable to excessive wear of the working parts. This accounts for the fact that their output tends to decrease very rapidly. It is an object of the present invention to provide an improved oscillating sanding machine of the kind referred to above.
According to the invention, this object is achieved by the provision of a sanding device of the above discussed type wherein the driving unit incorporates an unbalanced rotor which is pivoted on the work-plate or sanding table and, in consequence of its unbalance, causes the sanding plate which is resiliently suspended from the casing of the oscillating sanding device, to perform reciprocating oscillations.
The basic concept of the invention is founded on the provision of a relatively large-sized drive for the work-plate or sanding plate, which is supported inside a casing which is connected with the work table or sanding table. It is advantageous to support the rotor in a recess in the sanding plate, and to give the latter the additional function of a casing for the drive unit. With this arrangement, the design is extremely simple, the cost is moderate, and the efficiency is increased, losses of drive-energy being extremely small.
In addition, the use of resilient elements between the sanding plate and the main body of the vibratory sander to which it is attached, has been found to be advantageous. Also, a valve system, located in the main body of the vibratory sanding device, and incorporating a tappet with a push-button which interacts with a lever attached to a valve member and enables the latter to be tilted relative to the valve seat, is preferably provided.